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Residential wiring problem. Power in both positive and negative outlet.

Helping Pops out on this one... He's got a spare room with a small adjoining bathroom. The wiring breakdown on the fusebox indicates that these two rooms are wired as part of the same circuit on the main breaker. In the two rooms there are: 2 outlets, 1 GFI outlet, and 4 switches controlling 2 lights and 1 bathroom ceiling fan. In the last few months this room has been experiences some abnormalities in power: flickering lights, occasional outage, GFI tripped. The outages usually lasted less than an hour and would occur with or without any load and any time. GFI trips sometimes, but other lights will work on the circuit when it's just the GFI. Recently all power to this room has stopped. The main breaker never trips.

With everything unplugged (including the ceiling fan) I checked the outlets in the room. Screwdriver voltage tester was used. The probe registers a 'charge' in the outlet and 'no power' on the return. Normal. However when any load (light, clock, tv) is applied all outlets instantly register a charge in both the positive and the return. Not normal. The breaker doesn't trip, resetting breaker or GFI doesn't work, and the positive and negative terminals of the outlets are both registering as charged.

House is 10 years old with no previous wiring issues, in Canada. Can anyone tell me what's wrong?

edit: January 24, 2011 Problem has been located and fixed. Closer inspection of the breaker panel revealed that the neutral was loose, and had started to melt the casing of the wire. The wire was clipped and spliced, and now things are back to normal. Thanks for everyone's input, best answer awarded!

+2. Return/Neutral wire is out. It reads zero without load, and with a load connected, reaches the same potential as the Live/Hot wire.

Obviously you have checked the connections at the switchboard and tested every outlet on the circuit and the result is the same for each. Do you have power/light/fan on the same circuit over there? If so you will need to remove all the switches, outlets, covers etc. from the walls and ceilings and look for a loose/broken/burnt connection.

If this doesn't find a problem, you will need to check for evidence of vermin damage (including termites).

If this doesn't help, PM me and I can give you some tips on fault finding/troubleshooting and replacing the damaged bits without the need for specialist equipment. I was an electrician in a past life.

Sometimes outlets are wired by pushing the wire into the little terminal-holes instead of wraping the wire around the screw-terminal. The terminal holes work ok USUALLY but i have seen occurances where they dont maintain contact. The house is 10 years old... that means the OUTLETS are ten years old also. It wouldn't cost much to just replace all the plugs and switches you mentioned. Here in the USA, those items only cost about a dollar each. So it should only take a couple hours and ten bucks to replace them. Do them ONE AT A TIME and check with a circuit tester before proceeding to the next one. Also, your test screwdriver only indicates if the HOT terminal is hot. It doesn't really test the neutral terminal. Don't forget to check the terminals in the overhead ceiling lights and fans. Sometimes the twist-nut-terminals have a wire NOT QUITE in the nut and it becomes intermittent. Also... when you have the breaker OFF for those outlets... do a quick check of other outlets and lights in the entire house. Any outlet that is OFF with that breaker is ALSO SUSPECT... so you will want to replace those wall outlets also.

Insert in socket, no ground from probe.Hot line lights up probe, return doesn't. Then, after load is introduced, return line lights up too. With no return in any outlet in the circuit the loads do not operate.